FOREIGN Minister Julie Bishop has condemned those behind the Bangkok bombing that has killed at least 19 people, describing the terrifying explosion as a "dreadful act".

"The thoughts of all Australians are with the injured and the families of those who have lost their lives through this dreadful act," she said in a statement released today.

"I have spoken with our Ambassador in Bangkok this morning and I can confirm that the Australian Embassy is working closely with Thai authorities.

"There is no evidence at this stage that Australian nationals are among the deceased or seriously injured.

"Australia will continue to liaise closely with Thai authorities in relation to this attack and will work to strengthen our bilateral and regional counter-terrorism cooperation".

Bomb blast rocks Bangkok tourist area, killing at least 19

A bomb exploded at a popular shrine in central Bangkok during evening rush hour Monday (Tuesday AU time), killing at least 19 people, injuring more than 100 and leaving body parts strewn across the streets of a neighbourhood full of five-star hotels and upscale shopping malls, officials said.

No one immediately claimed responsibility for the blast, which caused the worst carnage of any single attack in recent memory in the Thai capital.

When Ms Gaffaney got to the scene of the bombing the area was closed off and there was a big military and police presence.

"Khao San Rd, the party street where all the expats and all the tourists hang out was closed. It was a lot quieter on the streets."

Ms Gaffaney is staying at a hostel, where the news was filtering through.

"Everyone's quite worried about it, quite stressed.

"People are calling up family... Everyone's on their phones looking at what's happening."

She wasn't aware of anyone who was leaving the city immediately but some tourists planning to leave tomorrow weren't sure if their train was still going.

A Ministry of Foreign Affairs and Trade spokesman said there was no confirmed information on the nationalities of the blast victims.

"The New Zealand Embassy in Bangkok continues to seek information on the nationalities of victims and casualties from the explosion at the Erawan Shrine in Central Bangkok, and is liaising with local authorities."

There are 470 Kiwis registered on the SafeTravel website as being in Thailand and the spokesman encouraged New Zealanders there or about to travel there to register their details on SafeTravel.govt.nz.

Anyone with concerns about a family member in Bangkok can call the ministry on +64 4 439 8000.

Kiwis in Bangkok have been contacted by the ministry telling them about the blast and of "unconfirmed local media reports" other bombs were found nearby.

"New Zealanders in Bangkok are advised to avoid travel to downtown Bangkok for the time being. We recommend exercising heightened vigilance at this time, monitoring the media for updates and adhering to the instructions of local authorities at all times, including any restrictions on movement," the ministry's advice says.

"We recommend contacting family in New Zealand as soon as possible to let them know you are okay.

"There is currently no change to our travel advisory risk levels for Bangkok or Thailand. We continue to advise caution in most parts of Thailand, including Bangkok, due to the threat from terrorism and potential for violent civil unrest."

Bomb had 100m "destructive radius"

The Royal Thai Police Office confirmed that of the 19 dead victims, 12 died at the scene.

The described the bomb as an IED and said it was composed of three kilogrammes of TNT stuffed in a pipe and wrapped with white cloth.

The Bangkok Post reported that the bomb's "destructive radius" was estimated at 100 metres. Authorities quickly recovered an electronic circuit suspected to be part of the device about 30 metres from the blast scene.

National police chief Somyot Pumpanmuang rushed to the scene and all 438 city schools were closed for safety reasons, the Bangkok Post reported.

Deputy Prime Minister and Defence Minister Prawit Wongsuwan expressed condolences to the families of the dead and injured victims.

He told the Bangkok Postit was too soon to say if the attacks were politically motivated or terrorism.

"But it was clear that the perpetrators intended to destroy the economy and tourism, because it occurred in the heart of (Bangkok's) business district," he said.

He believed whatever the motivation for the attack, the goal was clear - human casualties.

Defence spokesman Kongcheep Tantrawanich described the attack as "the work of those who have lost political interests and want to destroy the 'happy time' of Thai people".

"It's an attempt to ruin Thailand's tourism image and cause damage to the country's business sector,"he said..

"The group behind the bomb must stop the savage act done to their fellow Thais and stop hurting the nation."

Bomb 'aimed to kill'

The area around Bangkok's Erawan Shrine is filled with hundreds of tourists, office workers and shoppers at any given time. Police said the bomb was made from a pipe wrapped in cloth.

"Whoever planted this bomb is cruel and aimed to kill," said national police chief Somyot Poompummuang. "Planting a bomb there means they want to see a lot of people dead."

The shrine is at a major intersection that was the centre of many contentious political demonstrations in recent years - raising questions about whether the bombing was politically linked.

But police said it was too soon to determine the attack's motive.

Security video showed a powerful flash as the bomb exploded at around 7 p.m.

At least 19 people were confirmed dead and 117 injured, according to the Narinthorn emergency medical rescue center.

The dead included Chinese and a Filipino, Somyot said.

Anusit Kunakorn, secretary of the National Security Council, said Prime Minister Prayuth Chan-ocha, the former army chief who orchestrated the May 2014 coup, was closely monitoring the situation.

"We still don't know for sure who did this and why," Deputy Prime Minister Prawit Wongsuwon told reporters.

"We are not sure if it is politically motivated, but they aim to harm our economy and we will hunt them down."

Although Bangkok has seen a period of relative calm since last year's coup, there has been some tension in recent months, with the junta making clear that it may not hold elections until 2017 and wants a constitution that will allow some type of emergency rule to take the place of an elected government.

Stirring the pot has been former Prime Minister Thaksin, who was ousted in a 2006 coup and fled the country to avoid a corruption conviction.

Last week, Thaksin posted a message on YouTube urging his followers to reject the draft constitution because he said it was undemocratic.

The draft charter is supposed to be voted on next month by a special National Reform Council. If it passes, it is supposed to go to a public referendum around January.

Another source of recent tension is the annual military promotion list, with the junta's top two leaders - Prime Minister Prayuth and Deputy Prime Minister Prawit - widely believed to be supporting different candidates.

The reshuffle, which comes into effect in September, has traditionally been a source of unrest, as different cliques in the army, usually defined by their graduating class in the military academy, seek the most important posts to consolidate their power.